Electrical signaling system.



E No. 673,376. Patented May 7, l90l.

H. R. BENNETT] ELECTRICAL SIGNALING SYSTEM.

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No. 673,376; Patentod May 7, 19m.

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ELECTRICAL SIGNALING SYSTEM.

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UNITED STATES PATENT OFFICE.

HARRY R. BENNETT, or sAN FRANCISCO, CALIFORNIA.

ELECTRICAL SIG NALING SYSTEM.

SPECIFICATION forming part of Letters Patent No. 673,376, dated May 7,1901.

Application filed August 9, 1900. Serial No. 26,411. (No model.)

To all whom it may concern:

Be it known that I, HARRY R. BENNETT, a citizen of the United States,residing at San Francisco, in the county of San Francisco and State ofCalifornia, have invented certain new and useful Improvements inElectrical Signaling Systems, of which the following is a specification.

My invention relates to the electrical transmission of signals,and isparticularly adapted to the calling devices on party-line telephonesystems.

My object is to produce electrical signals with certainty and inrelation to telephone systems to supply a practical and effectivesignal-selector for party-lines by means of which any signal-bell on aparty-line of telephones can be rung without affecting or operating theother bells on that line. I send from the central station an electricalimpulse or impulses which will traverse every telephone in the circuit,but will be receivedand do work only at one designated instrument.

My apparatus comprises a number of vibrating transmitting devices and anequal number of vibrating receiving devices, one of which receivingdevices is capable of vibrating in synchronism with one of saidtransmitting devices while out of synchronism with all the others.Electrical impulses will be generated by vibrations of the transmitterand will be received and will operate at the single receiving instrumentwhose vibrations are synchronous therewith.

The invention can be applied to any ordinary party-line installation,since a single wire with the customary ground-return is all that isrequired.

A practical embodiment of my invention is shown in the accompanyingdrawings, in which- Figure 1 is a front elevation of one of thevibrating transmitting devices at a central station and shows thepole-changing switch in normal position or at rest. Fig. 2 is a sideelevation of the same. Fig. 3 is an elevation of the pole-changingswitch similar to Fig. 1, but showing it in its second or reversedposition. Fig. 4 is an elevation of the receiving device. Fig. 5 is anelevation of the bell and the intermediate solenoid whose core acts as abell striker or hammer. Fig. 6 is an end lar pair of transmitters andreceivers.

elevation of the said solenoid. Fig. 7 is a diagram of the whole system.Fig. 8 is a detail view of one of the polarized magnets. Fig. 9 is adetail view of an adjustable slide for regulating the frequency ofvibration of the receiving-vibrator.

Referring first to Fig. 7 for a general understanding of the wholesystem, the centralstation apparatus is shown at the lower part of thefigure and the party-line stations at p the upper part.

The central-station generator G is in normal open circuit through thebus-bars 1 2 with the vibrating transmitters '1, of which four are shownand each of which is provided with a circuit-closing button B. The lineis shown at L and the four corresponding vibrating receivers at R. Eachtransmitting-vibrator is an elastic arm fixed at one end and carrying atthe free end an armature for a polarized magnet M. The severaltransmitting-vibrators are of different lengths, as shown, and thereceiving-vibrators are also of different lengths relatively to oneanother, although each one corresponds in length to one of thetransmitting-vibrators.

' lhese variations in length account for difierent periods of vibrationand make it possible to synchronize the vibrations of a partic n- Forgreater accuracy in this respect the receiving-vibrators are providedwith adjustable slidess, by the movement of which along the arm theperiod of vibration can be regulated if not normally exact. Thereceiving-vibratorsare preferably in local relay-circuit with thebell-striker through the telephone-battery cells C at each station.Referring now to Figs. 1 and 2 in connection with Fig. 7, eachtransmitting vibrator carries a pole changing switch S S and aninsulated double platinum contact P P. The latter is connected by a wireW to the button B, through which button and the correspondingtransmitter the circuit can be closed at will. The contact P P islocated between the arms of the switch, which are preferabl y providedwith adjusting screw-contacts 10 p. This pole-changing switch and theplatinum contact on the vibrator cooperate with two other elastic arms LL, which I term lagging vibrators, because their period of vibration islonger than that of arm T, which makes them lag or follow the saidcontacts as they vibrate. In order to insure su ch greater length Q vibat h be Wei h ed a indicated at L They are fixed to the support A attheir lower ends,and their upper free ends respectively project betweencontacts S and P and contacts S and P. They are adjusted as to tensionby springs q q and screws g 1 Figs. 1 and 7 represent them as in normalor rest position and respectively in contact with points S and P, thecircuit being open and no current passing. In this condition themagnetomotive force of the polarized magnet M is derived only from itscores and is only suflicient to partially attract the armature M on thevibrator T. When the circuit is closed by buttonB, the course-of thecurrent is through wire W, contact P, lagging vibrator L, magnet M,through the line, in shunt through all the receivermagnets N, backthrough the line to lagging vibratorL, switchcontact P, vibrating arm T,and a connectingwire W to the other bus-bar 2. The magnetomotive forcein the coils of magnet M is added to the normal magnetomotive force ofthe cores and the armature is pulled sharply toward the magnet, movingthe transmitter-rod T, the switch, and both lagging vibrators in thesame direction. As the latter have a longer period of vibration,however, they contin ue their movement after the tension of thetransmitter-arm has overcome the magnetomotive force of the magnet.Temporarily, the said tension and the double magnetometive force areabout equal and thetransmit tor-arm and'armaturev rest, as it were, insuspension, while the laggingvibrators leave the contacts S and P andbreak the circuit. This releases the. extra magnetomotive force in themagnets. The tension. oftransmitt-er-rod T,

resulting from its attraction and the extra magnetomotive force towhichit has been exposed, is so. great that upon thebreaking offormernormalposition, carrying the lagging.

vibrators with it. On the cessation of itsperiod or length of .vibrationthe laggingvibrators continue their movement, reestablish theoriginalxcontacts, reverse the current, and double the magnetomotiveforcei-n the magnet M. Of course such an analysis as above of themovements of these parts conveys no idea of the actual and-extremerapidity of; the movementin vibration. I

In practice the operation is as follows: When it is desired to callreceiving-station No..1,-the.button B in transmitter No. 1 ispressedandthe current in alternating impulses,a .s described,divides andflows in shunt through all the receiving-magnets. Since eachtransmitter-rod has a definite rate or period of vibration and thecorresponding receiverrod is in synchronism with it alone and all otherreceiver-rods are non-synchronous and have a dilferent rate or period,only the receiver-rod at station No. 1 will take up the current impulsesso as to do work. If station No. 2 or 3 0I'4=iS to be called,'thecorresponding transmitter. is thrown into the circuit and the desiredstation only responds to the alternating impulses transmitted.

Since the rapidity and delicacy of vibration in the receiving-rods. makeit inconvenient to cause them to do actual mechanical Work, it ispreferred to operate. the bellssignal by arelay in the localtelephouercircuit, which in-- cludes the local batteries 0 and thesolenoid H, whose rapidly-vibrating core forms the bell-striker.Thevibratingreceiver-rod sue: cessively makes and breaks contacts at r.with a spring h, electrically connected to the solenoid H, Fig. 7. Thedetails. of Y the latter are shown in Figs. 5 and 6.

ing projection H3 atthe upper. end and acts itselfby gravity as thestriker at the. other, being situated between the two call-bells. Ascircuit is. closed and broken at r the successive, attractions andreleases of the core produce a rapid vibratory motion between the, twobells, which are alternately struck. The construction of' the solenoid,its hollow core, and the. diamagnetic. cap or projection has severalpeculiar featu res. Since. the core or plunger is designed to vibratewith very great rapidity, it must not betoo heavy to respond to thelimited electrical impulses, but must be heavy enough. tostrike thelowerhell by gravity with sufliicient force. The 5 central passage or bore ofthe solenoid should be substantially filled by the core in'order thatthe latter, may be. kept approximately in axialv parallelism withthecoil and with the proper line ofmotion, so that the whole force vlottheblow will be. delivered upon the bell .without lost motion. Ncwthecentral pas- .sage should be of comparatively large. sec- ;tional area,since. the. strength of a magnet is ,in inverse proportion to the lengthof thesog lenoid and in direct proportion to thesectional iarea, and inthis case the solenoid must beof @sufficient length to preventthe lowerend of lithe core from getting too far out of the magjnetic field orinfluence. Hence tor bothreasons the light hollowcore of.correspondingly llarge. circumferen ce. is employed.

The diamagnetic cap. or striker on the up-v per endof the hollow core isused to increase gthe effective or mechanical length ot the core withoutincreasing its magnetic. length. The 'magnetomotive force of the coiltends 1 to ,draw the center of magnetism, of the core or plunger towardthe center of magnetism of the coil, and the former ,should be at a.dis- Thecore; H is hollow and is provided with a diamagnetic strik-.

tance below the latter, so that the magnetomotive force shall have aconsiderable range of suction before the centers meet and neutralize theaction of the magnetomotive force. If the cap were not employed,themagnetic part of the core would be obliged to come past the upper partof the coil and partly out of the magnetic field, and if the magneticcore were made longer it would raise its own center of magnetism, and soreduce its own efiective vibration.

Fig. 8 shows in detail the winding for all the polarized magnets.

' In 'the condition of Fig. 1 the current enters at X and leaves at X,forming a positive pole at Y and a negative pole at Z, in conjunctionwith the normal polarity of the magnet cores, the magnetomotive forcebeing doubled. In the reversed condition of Fig. 2 the current enters atX and leaves at X, forming a positive pole at Z and a negative pole atY, in opposition to the normal polarity, and the magnetomotive force isaccordingly neutralized.

While I have described the use of means for producing an alternatingcurrent and prefer to use such a current in most cases, it is evidentlypracticable to use a direct current if the resistance in the circuit benot too great to render the operation uncertain. The modificationrequired will be easily understood by any one skilled in the art. Theelectromagnets will not be polarized, and for the polechanging devicecarried by the transmitterarmature will be substituted a single cont-actfor such armature, which is made and broken by its vibration.

I do not limit myself to details of construction and arrangementdescribed herein and shown in the drawings, as I desire to avail myselfof such modifications and equivalents as fall properly within the spiritof my invention.

Having thus fully described my invention, what I claim as new, anddesire to secure by Letters Patent, is-

1. A signal-selecting system for telephones, comprising alarms atsubscribers stations, a number of dissimilarly-vibrating central-stationtransmitters, a pole-changing switch at each transmitter for causingrapid successive alternations in the current, a number of vibratingreceivers at subscribers stations arranged respectively in synchronismwith said transmitters, and means derived from the vibrat-ion of anyreceiver for sounding the alarm at that station.

2. A signal-transmitter comprising a polarized electromagnet, avibrating armature, and a pole-changing switch operated by the vibrationof said armature for causing successive alternating-current impulses.

In a signaling system, a sourceof electrical energy, means for producingrapid successive alternations in the current derived therefrom, and asignaling device together with a polarized electromagnet and a vibratingarmature at the receiving-station, said vibrating armature beingoperated by changes in said electromagnet produced by said alternations,and means for causing the vibrations of said armature to operate thesignal means.

4. In an electrical signaling system, a bell in combination with amagnet arranged in proximity thereto, and means for energizing saidmagnet whereby its armature operates as a bell-striker.

5. In an electrical signaling system, a pair. of call-bells, incombination with an intermediately-arranged solenoid and means forcausing its core to operate as a double bell-striker.

6. In an electrical signaling system, a pair of call-bells, anintermediately-arranged solenoid, the core or plunger of the same havinga diamagnetic extension, and electrical connections for alternatelyenergizing and deenergizing the solenoid, whereby said core op crates asa double bell-striker.

7. In a signal-transmitter, a polarized elec- 'tromagnet, an elasticarmature therefor having an ascertained period of vibration, apolechanging device carried by said armature, and a pair of laggingvibrators having a longer pe riod of vibration and operating inconjunction with said pole-changing device.

8. In a transmitter, a polarized electromagnet, an elastic armaturetherefor having an ascertained period of vibration, an insulated doublecontact carried by said armature, a pole-changing switch carried by saidarmature, a pair of vibrating arms of longer period than the armature,whose free ends are respectively interposed between one arm of saidpole-changing switch, and one member of said double contact, anelectrical circuit in which said devices are included, and acircuit-controlling button.

9. In a signaling system, a polarized electromagnet, an elastic armaturetherefor under tension which opposes the pull of said magnet, and whichis superior to the attractive power of the core, means for energizingthe coil of the magnet so as to overcome said tension, and an automaticcircuit-breaker and pole-changer, all constructed and arranged so thatwhen the circuit is closed the magnet is alternately energized to thecombined magnetomotive force of its core and its coil, and completelyneutralized,whereby the said armature is set in vibration.

In testimony whereof I have affixed my signature, in presence of twowitnesses, this 2d day of August, 1900.

HARRY R. BENNETT.

Witnesses:

L. W. SEELY, F. M. BURT.

